This project uses the Social Security Administration (SSA) matched Social Security earnings histories and W-2 earnings data to develop a new panel data set of 401(k) contribution behavior and a new measure of pension wealth from 401(k)-type pension arrangements for FIRS individuals. It then analyzes and documents the extent to which these data better measure 401(k) pension wealth through a comparison of these data with the self-reported pension wealth data from the employment sections of the HRS and the firm-reported pension data calculated from the matched firm pension records. Finally, it makes available the new panel data set on 401(k) contributions and the new 401(k) pension wealth data to the research community.